Glycosylation and deglycosylation of proteasomes (prosomes) from calf-liver cells: High abundance of neuraminic acid

Proteasomes (prosomes) of calf-liver cells were probed with three different biotinylated lectins: Limulus polyphemus agglutinin (LPA), specific for neuraminic acid; Solanum tuberosum agglutinin (STA), specific for GlcNac; and concanavalin A (Con A), specific for Man/Glc. While only one proteasomal protein reacted with STA, most of the proteasomal proteins reacted with LPA and several with Con A. Deglycosylation with N-glycosidase F showed that the detected glycan residues were asparagine-linked. Finally we demonstrate an alternative method for the isolation of proteasomes based on the affinity of certain proteasomal proteins to Con A.